Transformer with regulable output current



Sept. 11, 1951 B. T. PEDERSEN 2,567,617

TRANSFORMER WITH REGULABLE OUTPUT CURRENT Filed Jan. 29, 1946 226 M q [MW Patented Sept. 11, 1951 TRANSFORMER WITH REGULABLE OUTPUT CURRENT Birger Thorleif Pedersen, Smestad, pr. Oslo,

Norway Application January 29, 1946, Serial-NoV644,151

In Norway January 30,1945- The present invention relates to electric transformers wherein the output current may be regulated within wide limits, and it is the object of the invention to provide such improvements in transformers of this kind that a very wide regula tion range may be obtained without the use'of reactance coils, while movable contacts and the like are avoided to the greatest possible extent.

According to the invention this object is eflected by a transformer provided with one or more secondary windings arranged on a common iron core, and with one or more magnetic shunts so arranged that the reluctance of the magnetic circuit through one or more of the secondary windings may be regulated, whereas the reluctance of the magnetic circuit or circuits of the remaining secondary or secondaries is substantially constant, and the individual secondary windings are so arranged as to be capable of working individually or in parallel.

In operation, any desired output current may be obtained by adjusting the reluctance of the magnetic circuit by simultaneous regulation of one or more of the magnetic shunts and parallelling of the so regulated winding or windings to one or more of the secondary windings, the magnetic circuit of which is of constant reluctance. In this way a continuous sequence of current values may be obtained, from the smallest current intensity by using one secondary only with the magnetic shunt regulated to its innermost position, to the heaviest current intensity by using all secondaries in parallel, the regulable shunts being then in their outermost position.

To this end it is especially desirable to make the various secondary windings of such dimensions that the current output of the winding or windings having magnetic shunts, when the shunt is in its inner position, is equal to or substantially equal to the current output of the winding or windings having magnetic circuits of constant reluctance. The current output which corresponds to the outer position of the magnetic shunt of one or more windings is then immediately followed, in the sequence of current values, by the current output of one or more non-regulable secondaries, the final adjustment of the total output current of the transformer being accomplished both by paralleling the secondaries as required and, at the same time, adjusting the magnetic shunt or shunts. By using a plurality of secondary windings a very wide regulation range may be obtained, and the current output may be adjusted to any value within said range.

Fig. 1 is a diagrammatic view of a transformer 1 Claim. (c1. 171-119) 7 Z in accordance with the invention, showing the iron core and winding arrangement,

Fig. 2 is a view, partly in section, of a transformer as shown in Fig. 1, as seen from the rightin Fig. 1, showing details of the shunt adjustment means.

In the embodiment shown, the transformer is provided with two secondary windings arranged one on each side of the primary winding, one of the secondaries being regulable and the other constant.

In Figure l, l is the iron core on which a symmetrical primary winding 2 and two symmetrical secondary windings 3 and 4 are arranged, magnetic shunt 5 and 6 being provided between the primary 2 and the secondaries 3 and 4 respec tively. In the drawing, each of the windings is arranged as two parallel coils, but obviously one or both may be arranged as one coil only, or again as two coils in series.

The connection between the two secondaries and also the selection of the number of turns of the individual windings may be effected by means of the stepping switch I, which may be adjusted to connect the welding spot 8 to a smaller or greater number of turns of one winding in parallel with a variable number of turns of the other winding.

During the operation of the transformer, the desired initial voltage may be adjusted by means of the switch 1, the working current being adjustable by means of the magnetic shunt 5, which in its inner position gives the minimum current intensity and in its outer position the maximum working current intensity. By means of the stepping switch I and the magnetic shunt 5, the transformer may thus be adapted to various welding methods, electrode dimensions and materials to be welded.

In Figure 2 an embodiment of the arrangement for the movement of the adjustable magnetic shunt is shown. For this purpose the transformer base member 9 is provided with a yoke construction comprising vertical support bars l0 and a transverse yoke l l, the latter being provided with a bearing I2 for a screw threaded bar l3 which is in threaded engagement with the shunt member 5 and, at its lower end, is supported by the base member 9. At the upper end, the bar [3 is provided with a handle [4 whereby the shunt member 5, by turning of the handle l4 and thus of the bar I3, may be moved perpefidicularly to the general plane of the iron core Obviously the details of this construction may be varied in numerous respects and do not form any part of the present invention.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

In a monophase transformer with adjustable output current, a common closed iron core, a common primary winding on said core, at least one secondary winding arranged on said core at either side of said primary winding, at least one magnetic shunt for the said common iron core disposed between the said primary and each secondary winding, the said magnetic shunt to one side of the said primary Winding being of 16 substantially constant reluctance and the said magnetic shunt to the other side of the said primary winding being of adjustable magnetic reluctance.

BIRGER THORLEIF PEDERSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Number Name Date Waters Apr. 27, 1926 Owen July 31, 1928 Burnengo June 3, 1930 Ross Nov. 17, 1931 Howard at al Jan. 14, 1936 Hathaway Apr. 18, 1939 FOREIGN PATENTS Country Date Australia May 20, 1937 Italy Mar. 18, 1935 

